If you look at the previous instruction 17+VEL to 18+ Ditch 1 L, it is supposed to be 1.4m below point 17+VEL. But is not. The side slope must have terminated at the ground surface, but is overshooting and creating an unwanted Ditch.

The instruction is identical on the RHS which is behaving properly.

If I delete the following template (2+165.01 Type 2), this corrects itself.

There seems to be some an extraneous instruction in here creating the ditch. The issue is at 2+053 the delta vertical is -1.4m from nodes 17 to 18. At the next template 2+165, the delta vertical is ~-3.2m from nodes 17 to 18. This distance between stations 2+053 and 2+165 interpolates from -1.4m to -3.2m, therefore around 2+150 this distance is ~-2.6m, this puts it below the surface. The next instruction draws to the surface as a cut or fill so this creates the ditch.

To resolve this, it seems that you just want to slope down from 17 to the surface, this could be accomplished by deleting the instruction from 17-18 and just leaving the one from 18-19 (this will become the new 17-18)

I'm not sure why the deleted instruction exists as the following one simply extended the line. This change may effect the rest of the project though.

I'm not sure why the templates were done this way but TBC seems to be interpreting it correctly. Hope that helps.